In a neutralisation reaction between an acid and an alkali, water is formed. Experiment to prove this.

NaCl(aq) + HCl(aq) = NaCl(aq) + H2O(l)

There must be equal amounts of hydrogen ions (from the hydrochloric acid) and hydroxide ions (from the sodium hydroxide) for the solution to be neutral.

Prediction: After some preliminary tests, I believe that as the concentration of alkali increases the amount of acid needed to neutralise it will increase.  This is because there are less hydroxide ions in 25cm of sodium hydroxide then there is hydrogen ions in 25cm of hydrochloric acid.

Diagram:

Method: I set up the apparatus as shown in the diagram.  I noted the starting position of the acid. I then added the acid gradually to the alkali using the burette.  The flask was swirled to let the acid and alkali mix. When the neutralisation was complete the indicator turned colourless showing me that I had to stop adding acid. I took a reading for the position of the acid and calculated the volume used.  I did this for 0.2M, 0.4M, 0.6M, 0.8M and 1M sodium hydroxide. I repeated the experiment and took the average so that my data was more accurate. I recorded my results in a table and drew a graph.

Results: I found my results contained no odd data.

Conclusion: I found that the higher the concentration the alkali was, the more acid needed to neutralise it.  This happens because the acid was kept at a concentration of 1M therefore less was needed for 0.2M alkali to neutralise it.  This was because the concentration of alkali was lower than that of the acid.  This meant that there were less hydroxide ions to be neutralised. As the concentration of the alkali increased the amount of hydroxide ions within the alkali also increased therefore needing more acid to neutralise it.